Dramatic shifts in Hawaiian monk seal distribution predicted from divergent regional trends (original) (raw)
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Aquatic Mammals, 2011
The Hawaiian monk seal is one of the world's rarest marine mammal species and is listed as depleted, endangered, and critically endangered based on national and international criteria. Although its precarious status was already recognized by the 1950s, it was not until the 1970s that direct protection was afforded to monk seals by U.S. legislation. Many important actions were taken to try and recover the population during the following four decades, including developing a population monitoring program; controlling impacts of military facilities in the Northwestern Hawaiian Islands (NWHI); managing fisheries to reduce their impacts; removing marine debris; and responding to other issues, including die-offs, inadequate nutrition, aggression by male seals, and shark predation. Recently, monk seals have reoccupied the main Hawaiian Islands (MHI). While this may be good news for their recovery, the MHI are well-populated by humans and significant management issues have appeared as seal numbers have increased. In spite of all that has been done, Hawaiian monk seals are likely to go extinct unless current conditions change. At this time, the most crucial needs for the recovery are (1) maintaining an adequate research and management program throughout the Hawaiian Archipelago; (2) continuing to minimize all sources of mortality; (3) promoting an increase in the number of monk seals in the MHI; (4) considering bold actions that could create more favorable conditions for seals in the NWHI; (5) ensuring that bureaucratic requirements and processes do not impede recovery actions; and (6) designing, funding, and implementing a set of actions that will stop the Hawaiian monk seal's decline toward extinction and recover the population sufficiently so that it can be removed from the Endangered Species Act's list of endangered species.
Managing for extinction? Conflicting conservation objectives in a large marine reserve
Conservation Letters, 2011
Establishment of the Papahānaumokuākea Marine National Monument (PMNM) in 2006 was heralded as a major advance for marine conservation. The PMNM is one of the largest no-take marine reserves in the world (36,207,439 hectares) and includes all of the Northwestern Hawaiian Islands (NWHI). Despite the protection, within its boundaries one of Hawaii's most charismatic marine species, the endemic Hawaiian monk seal (Monachus schauinslandi), is declining towards extinction. In contrast, monk seal abundance is increasing in the largely unprotected Main Hawaiian Islands. High juvenile mortality in the NWHI has been identified as the demographic factor responsible for the population decline. The ecological drivers of the dynamic are unknown. We evaluate an intervention proposed by the Pacific Islands Fisheries Science Center within the PMNM in a situation in which there is little or no precedent of theory to support management decisions, and then examine the conflicting conservation mandates that pose challenges for monk seal conservation. Benefits of intervention include the potential to maintain subpopulations in the NWHI, and therefore preserve the metapopulation structure, and it will provide additional time for management agencies to continue studies to understand factors limiting population growth. If conditions inside the PMNM do not improve, however, juvenile seals will continue to experience poor survival and subpopulations in the NWHI will continue to decline in spite of intervention. The long-term success of any intervention requires the underlying ecological reason for the NWHI population decline, which is currently unclear. The failure of the PMNM to conserve endangered Hawaiian monk seals highlights conflicting goals of different conservation agendas, the need to understand ecosystem function and large-scale ecosystem interactions, and the necessity of adaptive management.
Enhancing the Future of the Hawaiian Monk Seal Recommendations for the NOAA Recovery Program
Marine Conservation Institute , 2015
This report on the Hawaiian Monk Seal Recovery Program was undertaken by Marine Conservation Institute for the purpose of enhancing the conservation of one of the world's most endangered seals. In 2004, our attention was drawn to the continued population decline of the Hawaiian monk seal when we joined conservation organizations in Hawaiʻi to advocate for the establishment of a permanently protected marine reserve in the Northwestern Hawaiian Islands, the area where the majority of monk seals live. After Papahānaumokuākea Marine National Monument was created in 2006, we concluded that the monk seal, one of the monument's iconic species, needed to be a higher conservation priority for the National Oceanic and Atmospheric Administration (NOAA), the agency with legal responsibility for its recovery.
Proceedings of the Royal Society B: Biological Sciences, 2007
Estimates of variability in pinniped survival rates are generally based on observations at single sites, so it is not certain whether observed rates represent the whole population. Here, we provide a comprehensive analysis of spatio-temporal variation in age-specific survival rates for endangered Hawaiian monk seals (Monachus schauinslandi ) based on capture-recapture analyses of more than 85% of the pups weaned in this population over the last two decades. Uniquely, these data have been collected from six subpopulations, encompassing all major breeding sites across its 1800 km long core range. Analyses of individual subpopulations revealed similar patterns in age-specific survival, characterized by the relatively low survival rates from weaning to 2 years of age, intermediate rates to 4 years of age, and then by relatively high 'mature' survival rates until 17 years of age, after which a senescent decline was observed. Juvenile, subadult and adult survival rates all varied significantly over time. Trends in survival among subpopulations were coherent with their relative geographical positions, suggesting regional structuring and connectedness within the archipelago. Survival rates for different age classes tended to be positively correlated, suggesting that similar factors may influence the survival for seals of all ages.
Marine Ecology Progress Series, 2017
The Northwestern Hawaiian Islands share comparable biological community structures and have similar histories of fishing pressure, yet monk seal subpopulations show different trends of decline between locations. Using trophic models, we compared ecosystem structure and energy flows supporting 2 subpopulations (on Laysan Island and French Frigate Shoals (FFS) atoll), each with varied rates of decline (1998−2015). Through simulated perturbations, we showed that the Laysan community had much higher productivity and was mainly forced by bottom-up processes, but prey and predator abundance also controlled the energy flow and community structure. The FFS ecosystem was less productive and strongly influenced by a change in primary productivity. Although the FFS system responded to a change in predator and prey abundance, the monk seals were more influenced by benthic bottomfish biomass than by a change in predator abundance. We clarified the role of external drivers (Pacific Decadal Oscillation [PDO] and benthic bottomfish fishery): while the PDO did show correlation with monk seal population trends, the best models were driven by prey biomass as impacted by bottomfish removals. However, monk seal predator and prey trophic dynamics were not sufficient to explain the observed decline in monk seal biomass. We suggest that other factors amplifying mortality played a role; for example, shark predation on monk seal pups at FFS. Because of the uncertainties inherent in a complex ecosystem model, the results cannot be used for tactical management but they can help direct management or future research efforts in the recovery of the endangered monk seal population.
Reproductive Patterns of the Hawaiian Monk Seal
Marine Mammal Science, 2007
We evaluated reproductive patterns of the Hawaiian monk seal (Monachus schauinslandi) using a combination of fitted age-specific reproductive curves and analysis of reproductive patterns of individual females. We review the difficulties inherent in the acquisition and modeling of reproductive data with emphasis on the significance of reproductive senescence to populations with dissimilar age/sex compositions. Validation of the fitted reproductive parameters was accomplished by Monte Carlo sampling of parameter distributions to compare the expected number of pups with the observed production. Although the fitted reproductive functions appear to provide an acceptable fit to the raw reproductive data, we found that the fitted curves did a poor job of predicting the actual pup production in individual years because of high variability among years. To further verify, and elaborate on, the patterns in the pooled (multi-seal, and multi-year) rates, we examined attributes of the reproductive performance of individual seals. The attributes included age of primiparity, reproductive rates computed over several age ranges, and the relationship between reproductive performance and seal longevity. Analysis of individual seal patterns reinforced the conclusion that reproductive senescence is operative in monk seal populations.
Conservation biology for suites of species: Demographic modeling for Pacific island kingfishers
Biological Conservation, 2007
Island avifauna Micronesian kingfisher Pacific island conservation Population model Population suite Todiramphus cinnamominus reichenbachii Halcyon cinnamomina A B S T R A C T Conservation practitioners frequently extrapolate data from single-species investigations when managing critically endangered populations. However, few researchers initiate work with the intent of making findings useful to conservation efforts for other species. We presented and explored the concept of conducting conservation-oriented research for suites of geographically separated populations with similar natural histories, resource needs, and extinction threats. An example was provided in the form of an investigation into the population demography of endangered Micronesian kingfishers (Todiramphus cinnamominus).